This costs €2 to enter, and is a bit disappointing. There are much better looking gardens for free everywhere else in Madrid, so why should you pay to go in here? The gardens are several hundred years old, so perhaps their historic nature means pipes can’t be laid to improve the irrigation. Most plants looked pretty dried out, and the little box hedges were very small and spindly.
There were drinking fountains up near the conservatories, but the water was boiling hot, a marked contrast to the Retiro park. There was a lot of building work around the toilets so that there was a long diversion to reach them, although the toilets themselves were large and clean.
There were plenty of cacti in the conservatories, but anyone familiar with the Barbican conservatory wouldn’t be impressed.
My advice is, save money and just wander round the rose garden in Retiro!